The present invention relates to improved collar constructions. More particularly, the present invention relates to an improved arrangement for positively locking and locating an electrical lead.
In the description of the background of the present invention that follows reference is made to certain structures and methods, however, such references should not necessarily be construed as an admission that these structures and methods qualify as prior art under the applicable statutory provisions. Applicants reserve the right to demonstrate that any of the referenced subject matter does not constitute prior art with regard to the present invention.
It is common in many types of electrical devices to have an electrical lead which provides an electrical connection between components of the device and a power supply.
FIG. 1 is illustrative of such a device. The device of FIG. 1 will now be described for purposes of illustration.
FIG. 1 illustrates an electric furnace 1. Such furnaces are used, for example, in the semiconductor industry to heat semiconductor wafers. The electric furnace 1 includes an interior portion 3 which receives the articles to be heated (not shown). The interior portion is provided with thermal insulation 5, which is typically formed of a refractory material such as a ceramic fiber.
One or more heating elements 7 are also disposed in the interior portion 3. The heating element(s) 7 are commonly embedded in the thermal insulation 5.
Such furnace constructions are described in more detail in U.S. Pat. Nos. 4,596,922 and 6,125,134, both of which are incorporated herein by reference, in their entirety.
One or more electrical leads 9, 9xe2x80x2 are also at least partially disposed within the interior portion 3. An arrangement associated with one of these leads will now be described. The lead 9 can be at least partially embedded within the thermal insulation. The lead 9 generally comprises a first terminal portion 11 and a second terminal portion 13. One or more heating elements 7 are electrically coupled to the first terminal portion 11 via an electrical connector 15, and possibly through one or more internal bussing devices (not shown). The second terminal portion 13 of the lead 9 is electrically connected to power source (not shown).
The lead 9 passes through an electrically insulating collar 17, the collar 17 being attached to an exterior wall 18 of the furnace 1. Since both the lead 9 and the exterior wall 18 of the furnace are electrically conductive, the insulating collar 17 serves to prevent short circuiting by preventing contact between the lead 9 and the exterior wall 18 as the lead passes therethrough. The lead 9 is freely passed through the collar 17, in the sense that there is no mechanism which positively secures the lead 9 relative to the collar 17. The lead 9 is embedded in the thermal insulation 5, and in the illustrated device, the insulation 5 is in turn being compressed against the interior of the wall 18 of the furnace.
The above-described arrangement can be repeated about the circumference of the furnace 1, as indicated by reference numeral 9xe2x80x2.
The above-described arrangement can possess certain disadvantages.
As noted above, during construction of the furnace 1, the insulation 5 is compressed between at least the first terminal portion 11 of lead 9 and the interior surface of wall 18 of the furnace 1. This compressed insulation can produce an inward force on the first terminal portion 11, thereby causing the lead 9 to xe2x80x9csettlexe2x80x9d into the interior of the furnace.
The interior portion of the furnace is subjected to thermal cycling during the useful lifetime of the device. The different rates of thermal expansion of the interior components of the furnace, degradation of the insulating materials, etc. can all contribute to the above-mentioned settling effect.
Shocks, stresses, and/or forces applied to the portion of the lead 9 which extends beyond the exterior wall 18 and the collar 17, for instance at the second terminal portion 13, are transferred to the interior of the furnace 1 since the lead 9 is freely moveable relative to the collar 17. Thus, such externally applied shocks, stresses and/or forces represent another source of potential damage to the interior of the furnace 1.
There exists a need in the art for improved collar constructions, for improved arrangements for positively locking and locating an electrical leads, and for improved electric furnace constructions that more effectively prevent damage to the internal construction of such furnaces.
The present invention addresses the above-mentioned problems of the prior art, and others.
The present invention provides a collar and a locking element for positively locating the a lead passing therethrough and maintaining the lead in its proper position.
According to one aspect, the present invention provides an arrangement comprising an electrically insulating collar, the collar comprising: a mounting flange and a passageway; an electrically conductive lead disposed at least partially within the passageway; and means for securing the lead relative to the passageway such that the lead is maintained in its proper position.
According to another aspect, the present invention provides an electric furnace comprising: an interior portion; thermal insulation disposed within the interior portion; at least one heating element disposed within the interior portion; an electrical lead having a first terminal portion disposed within the interior portion and a second terminal portion disposed outside the interior portion; an electrical connector electrically connected to the at least one heating element and disposed on the first terminal portion; an exterior wall; an electrically insulating collar, the lead at least partially received within the collar; and means for securing the lead relative to the collar such that the lead is maintained in its proper position.
According to a further aspect, the present invention provides an arrangement for positively securing an electrical lead of an electric furnace, the lead passing from within the furnace to outside the furnace, the arrangement comprising an exterior furnace wall; an electrically insulating collar, the collar comprising a mounting flange attached to the exterior wall, and a passageway; an electrically conductive lead disposed at least partially within the passageway; and a fastener securing the lead relative to the passageway such that the lead is maintained in its proper position.